About 80 cases of monkeypox have been confirmed in 11 countries, said the World Health Organizaion (WHO) on Friday, warning that more cases are likely to be reported. The international health organization is also investigating over 50 suspected cases without naming any countries. 

The WHO Regional Director for Europe Hans Kluge warned that cases of the rare monkeypox virus could accelerate in the coming months, as the virus spreads across the Europe. "As we enter the summer season, with mass gatherings, festivals and parties, I am concerned that transmission could accelerate."

The virus, which causes distinctive pustules is rarely fatal, has previously been seen in central and west Africa. But over recent weeks cases have been detected in eight European countries including Portugal and Sweden as well as the U.S., Canada and Australia, Kluge said, calling the spread "atypical".

"All but one of the recent cases have no relevant travel history to areas where monkeypox is endemic," he added, warning that transmission could be boosted by the fact that "the cases currently being detected are among those engaging in sexual activity" and many do not recognize the symptoms which suggests that transmission may have been ongoing for some time.

The WHO has also said it is investigating the fact that many cases reported were people identifying as gay, bisexual or men who have sex with men.

'Increase in coming days'

The UK Health Security Agency's (UKHSA) chief medical adviser, Susan Hopkins, also said she expected "this increase to continue in the coming days and for more cases to be identified in the wider community." She particularly urged gay and bisexual men to look out for symptoms, saying a "notable proportion" of cases in the UK and Europe came from this group.

Monkeypox had not previously been described as a sexually transmitted infection, the UKHSA said. It can be transmitted through contact with skin lesions and droplets of a contaminated person, as well as shared items such as bedding and towels.

UK Health Secretary Sajid Javid sought to reassure the public, tweeting: "Most cases are mild and I can confirm we have procured further doses of vaccines that are effective against monkeypox." Symptoms of the disease include fever, muscle aches, swollen lymph nodes, chills, exhaustion and a chickenpox-like rash on the hands and face. 

Monkeypox usually clears up after two to four weeks, according to the WHO. 

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(With input from AFP)